Method of producing coated tablets

ABSTRACT

A method is described for manufacturing coated tablets made of tablet cores and coating granulate using a press that has at least one compression chamber with preferably an upper and a lower punch and a feeding device for tablet cores. 
     The method according to the invention is characterized by the fact that before the coating granulate is compressed, at least one pasty tablet core is added to the coating granulate to be compressed and in that the coating granulate and tablet core(s) are compressed in a single compression step.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to a method for manufacturing coated tablets fromtablet cores and coating granulate using a press that has at least onecompression chamber, preferably with an upper and a lower punch and afeeding device for tablet cores.

2. Description of the Related Art

Methods according to the related art are based as a rule on so-calledrotary tablet machines with a high processing speed.

The manufacture of coated tablets has thus far been performed in twosteps:

In the first manufacturing step the future cores of the coated tabletsare compressed and in the second step the tabletting material for thelower half of the coating is precompressed, the core is placed on theprecompressed bed, and is then compressed to form a coated tablet aftertabletting material for the upper half of the coating has been added tothe die.

The first manufacturing step can be further differentiated into aloading phase in which the tabletting material is added to the diecavity, a compression phase, and an ejection phase in which the finishedtablet is removed from the die with the aid of a lower punch.

The second manufacturing step conventionally consists of a first fillingphase in which the tabletting material for the lower half of the coatedtablet to be produced is loaded into the die, a precompression phase inwhich the tabletting material that has been added is precompressedslightly so that the core to be added can be placed, a metering phase inwhich the core is added to the precompressed bed, a second filling phasein which the upper half of the coating is loaded into the die, acompression phase to compress the coated tablet, and an ejection phasethat serves to remove the compressed tablet from the die with the aid ofthe lower punch.

DESCRIPTION OF THE INVENTION

The invention has as its goal the provision of a method formanufacturing coated tablets that simplifies the manufacture of coatedtablets and in which in particular only a single manufacturing step isrequired for.

According to the invention, the cores do not consist of tablet corespreviously manufactured in a separate compression process which areadded as solidified masses to the tabletting material, but insteadconsist of a pasty preparation of the contents in a dispersing agent,such as alcohol or Miglyol™ for example. This makes it possible to addat least one pasty tablet core to the coating granulate to be compressedbefore compressing the coating granulate. Then the coating granulate iscompressed along with the tablet core in a single compression step.

In particular, the method according to the invention makes it possibleto add at least two tablet cores, separated from one another, to thetablet in such fashion that the surrounding granulate prevents therespective contents of the tablet cores from engaging in chemical orphysical reactions with one another. For this purpose, contents can beprovided in a tablet that would enter into undesired reactions if theywere processed together.

The pasty tablet core or cores can be added in many different ways.However, preferably, the pasty tablet core mass has a consistency andespecially a viscosity such that the tablet core mass is injected bymeans of a high-pressure feed shoe into the coating granulate.

However, the following problem occurs when the tablet core or cores areadded:

By combining the two manufacturing steps, separate in the prior art,into a single manufacturing step, the metering and division of thetablet cores, which is accomplished in the prior art by separatecompression of the tablet cores, must take place during the addition ofthe tablet core masses to the tabletting material of the tablet coating.As a result, the pasty tablet core mass must be divided into portionswhose volumes must be metered precisely.

For this reason, in a preferred embodiment of the invention a meteringdevice is provided that must meet the technical demands of maximallyprecise mass flow metering. This metering device consists of aProportional valve.

The high metering accuracy of the tabletting core mass that is achievedin compressed tablet cores by the parameters that are conventional intablet manufacture (volume of die cavity, density of tablettingmaterial) and control values (press pressure, compressive strength), atthe high processing rates that rotary tablet machines in particular canachieve (60,000 tablets or more per hour), is achieved by apiezoelectric proportional valve that operates in proportion to thecontrol and which by adjusting the through flow volume and crosssection, permits precise direct injection of the highly concentratedmass into the tabletting material, which would not be possible withconventional valves. This piezoelectric proportional valve is preferablycontrolled by a computer or an electronic control unit. In addition,sensors for pressure, temperature, etc. can be provided whose outputsignals are fed to the control computer for the proportional valve orvalves.

The proportional valve used according to the invention can producepressures from 30 to 50 bars and frequencies of 4 kHz, with onemanufacturing step lasting 50 microseconds.

Another improvement on the method according to the invention relates tothe compression chamber which is initially partially filled with coatinggranulate, then the pasty tablet core or cores are added, and the presschamber is filled completely with coating granulate. The coatinggranulate added to the compression chamber can be precompressed beforethe tablet core or cores are added.

This improvement has the particular advantage that after precompression,a film substance, conventionally used for external film coating oftablets, can be applied to the tablet core or cores. The film substanceis applied after precompression for example.

The same substances found in the known “external film coating” oftablets, possibly in a higher concentration may be used. To apply thefilm or films, a high-pressure spray device with a computer-controlledproportional valve can be used. The same computer-controlled piezoeleticproportional valves used for metering tablet cores can be used asproportional valves.

The “internal coating” of coated tablets proposed according to theinvention has the further advantage that tablet cores spaced apart fromone another an be film-coated with different substances. The substancesof the individual films can have certain different disintegrationproperties and/or different encapsulated active substances and/ordifferent formulations. As a result, retard forms are obtained thatoffer different disintegration times in a single dose for example. Ofcourse the coated tablets produced by the method according to theinvention can be “externally film-coated” in addition or exclusively.

The method according to the invention also makes it possible to makevery large tablets which, have no hydrophobic lubricant inside thetablets that retards dissolution, and thus dissolve faster thanconventional tablets of the same size. This smaller added amount oflubricant is achieved by the application, known of itself, of thelubricant to the walls of the compression chamber in contrast to theknown direct admixture of the lubricant with the tablet material. As aresult, the generation of CO₂ that is required in conventionaleffervescent tablets to increase the dissolution rate can be eliminated.

The CO₂ that is produced here for example by at least two tablet cores,one of which consists of a conventional hydrogen carbonate and the otherof a conventional acid, can be used as an indicator for the completedissolution of the coating which in this case contains activesubstances, flavorants, and other additives or is used to improve thetaste.

The additive for example is an adhesive gel former that prevents theCO₂-forming substance from floating as a result of the gas formationthat occurs during activation.

It should be made expressly clear that the term “tablet” used above isnot limited to tablets in the pharmaceutical area alone. This termwithin this application also subsumes “bonbons” or other “tablet-like”objects. In the food area, pasty cores of chocolate or cocoa butter arepossible for example. The cores can also contain freeze-dried pieces offruit and/or pastes. Cores are also possible that consist of severaldifferent layers.

What is claimed is:
 1. Method for manufacturing coated tablets fromtablet cores and coating granulate using a press that has at least onecompression chamber, and a feed device for tablet cores, comprising:adding at least one pasty tablet core to the coating granulate to becompressed, and compressing the coating granulate and the tablet coressimultaneously in a single pressing step.
 2. Method according to claim1, wherein at least two tablet cores separate from one another are addedto the coating granulate.
 3. Method according to claim 1, wherein theconsistency and the viscosity of the pasty tablet core mass are such asto inject the tablet core mass into the coating granulate by means ofhigh pressure feeding means .
 4. Method according to claim 3, wherein aproportional valve is used for metering the tablet core mass added bythe high pressure feeding means.
 5. Method according to claim 4, whereinthe cross section and the throughput volume of the proportional valveare adjustable by computer controlled piezoelectric means.
 6. Methodaccording to claim 1, wherein the compression chamber is initiallypartially filled with coating granulate, then after the at least onepasty tablet core is added, additional coating granulate is added to thecompression chamber to completely fill the compression chamber. 7.Method for manufacturing coated tablets from tablet cores and coatinggranulate by means of a press with at least one compression chamber anda feed device for tablet cores, comprising: (a) adding the coatinggranulate to compression chamber; (b) precompressing the coatinggranulate in the compression chamber; (c) after step (b), adding a pastytablet core to the core to the compression chamber; and (d) compressingthe coating granulate simultaneously with the tablet core.
 8. Methodaccording to claim 7, wherein a film substance is applied to the tabletcore after precompression.
 9. Method according to claim 8, whereintablet cores spaced apart from one another are film-coated withdifferent substances.
 10. Method according to claim 9, wherein thedifferent substances differ in terms of their disintegration time. 11.Method according to claim 8, wherein high-pressure high-pressure feedingmeans with a computer-controlled proportional valve is used for applyingthe film substance.
 12. Method according to claims 11, wherein acomputer-controlled piezoelectric proportional valve is used as thevalve that operates in proportion to the control and whose throughputvolume and cross section are adjustable.
 13. Use of the method accordingto claim 1 to produce effervescent tablets which have at least twotablet cores, with one containing a hydrogen carbonate and anothercontaining an acid.
 14. A method for manufacturing coated tablets,comprising: (a) adding at least one pasty tablet core to a coatinggranulate; (b) simultaneously compressing the at least one pasty tabletcore and the coating granulate within a compression chamber of a presssuch that the at least one pasty tablet core and the coating granulateare compressed in a single pressing step; and (c) forming tablets inwhich material of the coating granulate surrounds material of the atleast one pasty tablet core.
 15. A method according to claim 14, whereinat least two pasty tablet cores, separated from another, are add ed tothe coating granulate.
 16. A method of according to claim 14, whereinthe at least one tablet core is added to the coating granulate in step(a) by injecting the at least one pasty tablet core from a high pressurefeeder.
 17. A method according to claim wherein 14, both a hydrogencarbonate pasty tablet core and an acid pasty tablet core are added tothe coating granulate, the pasty tablet cores being added separately toprevent chemical and physical reaction therebetween.
 18. A method formanufacturing coated tablets, comprising: (a) adding coating granulateto a compression chamber of a press; (b) precompressing the coatinggranulate; (c) after step (b), adding at least one pasty tablet core tothe coating granulate; and (d) compressing the coating granulatetogether with the at least one pasty tablet core to form tablets inwhich material of the coating granulate surrounds material of the atleast one pasty tablet core.
 19. A method according to claim 18, whereinat least two pasty tablet cores, separated from another, are added tothe coating granulate.
 20. A method of according to claim 18, whereinthe at least one pasty tablet core is added to the coating granulate instep (c) by injecting the at least one pasty tablet core from a highpressure feeder.
 21. A method according to claim 18, wherein both ahydrogen carbonate pasty tablet core and an acid pasty tablet core areadded to the coating granulate, the pasty tablet cores being addedseparately to prevent chemical and physical reaction therebetween.